1 /* $OpenBSD: cipher.c,v 1.82 2009/01/26 09:58:15 markus Exp $ */ 2 /* 3 * Author: Tatu Ylonen <ylo@cs.hut.fi> 4 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 5 * All rights reserved 6 * 7 * As far as I am concerned, the code I have written for this software 8 * can be used freely for any purpose. Any derived versions of this 9 * software must be clearly marked as such, and if the derived work is 10 * incompatible with the protocol description in the RFC file, it must be 11 * called by a name other than "ssh" or "Secure Shell". 12 * 13 * 14 * Copyright (c) 1999 Niels Provos. All rights reserved. 15 * Copyright (c) 1999, 2000 Markus Friedl. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38 #include "includes.h" 39 40 #include <sys/types.h> 41 42 #include <openssl/md5.h> 43 44 #include <string.h> 45 #include <stdarg.h> 46 47 #include "xmalloc.h" 48 #include "log.h" 49 #include "cipher.h" 50 51 /* compatibility with old or broken OpenSSL versions */ 52 #include "openbsd-compat/openssl-compat.h" 53 54 extern const EVP_CIPHER *evp_ssh1_bf(void); 55 extern const EVP_CIPHER *evp_ssh1_3des(void); 56 extern void ssh1_3des_iv(EVP_CIPHER_CTX *, int, u_char *, int); 57 extern const EVP_CIPHER *evp_aes_128_ctr(void); 58 extern void ssh_aes_ctr_iv(EVP_CIPHER_CTX *, int, u_char *, u_int); 59 60 struct Cipher { 61 char *name; 62 int number; /* for ssh1 only */ 63 u_int block_size; 64 u_int key_len; 65 u_int discard_len; 66 u_int cbc_mode; 67 const EVP_CIPHER *(*evptype)(void); 68 } ciphers[] = { 69 { "none", SSH_CIPHER_NONE, 8, 0, 0, 0, EVP_enc_null }, 70 { "des", SSH_CIPHER_DES, 8, 8, 0, 1, EVP_des_cbc }, 71 { "3des", SSH_CIPHER_3DES, 8, 16, 0, 1, evp_ssh1_3des }, 72 { "blowfish", SSH_CIPHER_BLOWFISH, 8, 32, 0, 1, evp_ssh1_bf }, 73 74 { "3des-cbc", SSH_CIPHER_SSH2, 8, 24, 0, 1, EVP_des_ede3_cbc }, 75 { "blowfish-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_bf_cbc }, 76 { "cast128-cbc", SSH_CIPHER_SSH2, 8, 16, 0, 1, EVP_cast5_cbc }, 77 { "arcfour", SSH_CIPHER_SSH2, 8, 16, 0, 0, EVP_rc4 }, 78 { "arcfour128", SSH_CIPHER_SSH2, 8, 16, 1536, 0, EVP_rc4 }, 79 { "arcfour256", SSH_CIPHER_SSH2, 8, 32, 1536, 0, EVP_rc4 }, 80 { "aes128-cbc", SSH_CIPHER_SSH2, 16, 16, 0, 1, EVP_aes_128_cbc }, 81 { "aes192-cbc", SSH_CIPHER_SSH2, 16, 24, 0, 1, EVP_aes_192_cbc }, 82 { "aes256-cbc", SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc }, 83 { "rijndael-cbc@lysator.liu.se", 84 SSH_CIPHER_SSH2, 16, 32, 0, 1, EVP_aes_256_cbc }, 85 { "aes128-ctr", SSH_CIPHER_SSH2, 16, 16, 0, 0, evp_aes_128_ctr }, 86 { "aes192-ctr", SSH_CIPHER_SSH2, 16, 24, 0, 0, evp_aes_128_ctr }, 87 { "aes256-ctr", SSH_CIPHER_SSH2, 16, 32, 0, 0, evp_aes_128_ctr }, 88 #ifdef USE_CIPHER_ACSS 89 { "acss@openssh.org", SSH_CIPHER_SSH2, 16, 5, 0, 0, EVP_acss }, 90 #endif 91 { NULL, SSH_CIPHER_INVALID, 0, 0, 0, 0, NULL } 92 }; 93 94 /*--*/ 95 96 u_int 97 cipher_blocksize(const Cipher *c) 98 { 99 return (c->block_size); 100 } 101 102 u_int 103 cipher_keylen(const Cipher *c) 104 { 105 return (c->key_len); 106 } 107 108 u_int 109 cipher_get_number(const Cipher *c) 110 { 111 return (c->number); 112 } 113 114 u_int 115 cipher_is_cbc(const Cipher *c) 116 { 117 return (c->cbc_mode); 118 } 119 120 u_int 121 cipher_mask_ssh1(int client) 122 { 123 u_int mask = 0; 124 mask |= 1 << SSH_CIPHER_3DES; /* Mandatory */ 125 mask |= 1 << SSH_CIPHER_BLOWFISH; 126 if (client) { 127 mask |= 1 << SSH_CIPHER_DES; 128 } 129 return mask; 130 } 131 132 Cipher * 133 cipher_by_name(const char *name) 134 { 135 Cipher *c; 136 for (c = ciphers; c->name != NULL; c++) 137 if (strcmp(c->name, name) == 0) 138 return c; 139 return NULL; 140 } 141 142 Cipher * 143 cipher_by_number(int id) 144 { 145 Cipher *c; 146 for (c = ciphers; c->name != NULL; c++) 147 if (c->number == id) 148 return c; 149 return NULL; 150 } 151 152 #define CIPHER_SEP "," 153 int 154 ciphers_valid(const char *names) 155 { 156 Cipher *c; 157 char *cipher_list, *cp; 158 char *p; 159 160 if (names == NULL || strcmp(names, "") == 0) 161 return 0; 162 cipher_list = cp = xstrdup(names); 163 for ((p = strsep(&cp, CIPHER_SEP)); p && *p != '\0'; 164 (p = strsep(&cp, CIPHER_SEP))) { 165 c = cipher_by_name(p); 166 if (c == NULL || (c->number != SSH_CIPHER_SSH2 && 167 c->number != SSH_CIPHER_NONE)) { 168 debug("bad cipher %s [%s]", p, names); 169 xfree(cipher_list); 170 return 0; 171 } else { 172 debug3("cipher ok: %s [%s]", p, names); 173 } 174 } 175 debug3("ciphers ok: [%s]", names); 176 xfree(cipher_list); 177 return 1; 178 } 179 180 /* 181 * Parses the name of the cipher. Returns the number of the corresponding 182 * cipher, or -1 on error. 183 */ 184 185 int 186 cipher_number(const char *name) 187 { 188 Cipher *c; 189 if (name == NULL) 190 return -1; 191 for (c = ciphers; c->name != NULL; c++) 192 if (strcasecmp(c->name, name) == 0) 193 return c->number; 194 return -1; 195 } 196 197 char * 198 cipher_name(int id) 199 { 200 Cipher *c = cipher_by_number(id); 201 return (c==NULL) ? "<unknown>" : c->name; 202 } 203 204 void 205 cipher_init(CipherContext *cc, Cipher *cipher, 206 const u_char *key, u_int keylen, const u_char *iv, u_int ivlen, 207 int do_encrypt) 208 { 209 static int dowarn = 1; 210 #ifdef SSH_OLD_EVP 211 EVP_CIPHER *type; 212 #else 213 const EVP_CIPHER *type; 214 int klen; 215 #endif 216 u_char *junk, *discard; 217 218 if (cipher->number == SSH_CIPHER_DES) { 219 if (dowarn) { 220 error("Warning: use of DES is strongly discouraged " 221 "due to cryptographic weaknesses"); 222 dowarn = 0; 223 } 224 if (keylen > 8) 225 keylen = 8; 226 } 227 cc->plaintext = (cipher->number == SSH_CIPHER_NONE); 228 229 if (keylen < cipher->key_len) 230 fatal("cipher_init: key length %d is insufficient for %s.", 231 keylen, cipher->name); 232 if (iv != NULL && ivlen < cipher->block_size) 233 fatal("cipher_init: iv length %d is insufficient for %s.", 234 ivlen, cipher->name); 235 cc->cipher = cipher; 236 237 type = (*cipher->evptype)(); 238 239 EVP_CIPHER_CTX_init(&cc->evp); 240 #ifdef SSH_OLD_EVP 241 if (type->key_len > 0 && type->key_len != keylen) { 242 debug("cipher_init: set keylen (%d -> %d)", 243 type->key_len, keylen); 244 type->key_len = keylen; 245 } 246 EVP_CipherInit(&cc->evp, type, (u_char *)key, (u_char *)iv, 247 (do_encrypt == CIPHER_ENCRYPT)); 248 #else 249 if (EVP_CipherInit(&cc->evp, type, NULL, (u_char *)iv, 250 (do_encrypt == CIPHER_ENCRYPT)) == 0) 251 fatal("cipher_init: EVP_CipherInit failed for %s", 252 cipher->name); 253 klen = EVP_CIPHER_CTX_key_length(&cc->evp); 254 if (klen > 0 && keylen != (u_int)klen) { 255 debug2("cipher_init: set keylen (%d -> %d)", klen, keylen); 256 if (EVP_CIPHER_CTX_set_key_length(&cc->evp, keylen) == 0) 257 fatal("cipher_init: set keylen failed (%d -> %d)", 258 klen, keylen); 259 } 260 if (EVP_CipherInit(&cc->evp, NULL, (u_char *)key, NULL, -1) == 0) 261 fatal("cipher_init: EVP_CipherInit: set key failed for %s", 262 cipher->name); 263 #endif 264 265 if (cipher->discard_len > 0) { 266 junk = xmalloc(cipher->discard_len); 267 discard = xmalloc(cipher->discard_len); 268 if (EVP_Cipher(&cc->evp, discard, junk, 269 cipher->discard_len) == 0) 270 fatal("evp_crypt: EVP_Cipher failed during discard"); 271 memset(discard, 0, cipher->discard_len); 272 xfree(junk); 273 xfree(discard); 274 } 275 } 276 277 void 278 cipher_crypt(CipherContext *cc, u_char *dest, const u_char *src, u_int len) 279 { 280 if (len % cc->cipher->block_size) 281 fatal("cipher_encrypt: bad plaintext length %d", len); 282 if (EVP_Cipher(&cc->evp, dest, (u_char *)src, len) == 0) 283 fatal("evp_crypt: EVP_Cipher failed"); 284 } 285 286 void 287 cipher_cleanup(CipherContext *cc) 288 { 289 if (EVP_CIPHER_CTX_cleanup(&cc->evp) == 0) 290 error("cipher_cleanup: EVP_CIPHER_CTX_cleanup failed"); 291 } 292 293 /* 294 * Selects the cipher, and keys if by computing the MD5 checksum of the 295 * passphrase and using the resulting 16 bytes as the key. 296 */ 297 298 void 299 cipher_set_key_string(CipherContext *cc, Cipher *cipher, 300 const char *passphrase, int do_encrypt) 301 { 302 MD5_CTX md; 303 u_char digest[16]; 304 305 MD5_Init(&md); 306 MD5_Update(&md, (const u_char *)passphrase, strlen(passphrase)); 307 MD5_Final(digest, &md); 308 309 cipher_init(cc, cipher, digest, 16, NULL, 0, do_encrypt); 310 311 memset(digest, 0, sizeof(digest)); 312 memset(&md, 0, sizeof(md)); 313 } 314 315 /* 316 * Exports an IV from the CipherContext required to export the key 317 * state back from the unprivileged child to the privileged parent 318 * process. 319 */ 320 321 int 322 cipher_get_keyiv_len(const CipherContext *cc) 323 { 324 Cipher *c = cc->cipher; 325 int ivlen; 326 327 if (c->number == SSH_CIPHER_3DES) 328 ivlen = 24; 329 else 330 ivlen = EVP_CIPHER_CTX_iv_length(&cc->evp); 331 return (ivlen); 332 } 333 334 void 335 cipher_get_keyiv(CipherContext *cc, u_char *iv, u_int len) 336 { 337 Cipher *c = cc->cipher; 338 int evplen; 339 340 switch (c->number) { 341 case SSH_CIPHER_NONE: 342 case SSH_CIPHER_SSH2: 343 case SSH_CIPHER_DES: 344 case SSH_CIPHER_BLOWFISH: 345 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); 346 if (evplen <= 0) 347 return; 348 if ((u_int)evplen != len) 349 fatal("%s: wrong iv length %d != %d", __func__, 350 evplen, len); 351 #ifdef USE_BUILTIN_RIJNDAEL 352 if (c->evptype == evp_rijndael) 353 ssh_rijndael_iv(&cc->evp, 0, iv, len); 354 else 355 #endif 356 if (c->evptype == evp_aes_128_ctr) 357 ssh_aes_ctr_iv(&cc->evp, 0, iv, len); 358 else 359 memcpy(iv, cc->evp.iv, len); 360 break; 361 case SSH_CIPHER_3DES: 362 ssh1_3des_iv(&cc->evp, 0, iv, 24); 363 break; 364 default: 365 fatal("%s: bad cipher %d", __func__, c->number); 366 } 367 } 368 369 void 370 cipher_set_keyiv(CipherContext *cc, u_char *iv) 371 { 372 Cipher *c = cc->cipher; 373 int evplen = 0; 374 375 switch (c->number) { 376 case SSH_CIPHER_NONE: 377 case SSH_CIPHER_SSH2: 378 case SSH_CIPHER_DES: 379 case SSH_CIPHER_BLOWFISH: 380 evplen = EVP_CIPHER_CTX_iv_length(&cc->evp); 381 if (evplen == 0) 382 return; 383 #ifdef USE_BUILTIN_RIJNDAEL 384 if (c->evptype == evp_rijndael) 385 ssh_rijndael_iv(&cc->evp, 1, iv, evplen); 386 else 387 #endif 388 if (c->evptype == evp_aes_128_ctr) 389 ssh_aes_ctr_iv(&cc->evp, 1, iv, evplen); 390 else 391 memcpy(cc->evp.iv, iv, evplen); 392 break; 393 case SSH_CIPHER_3DES: 394 ssh1_3des_iv(&cc->evp, 1, iv, 24); 395 break; 396 default: 397 fatal("%s: bad cipher %d", __func__, c->number); 398 } 399 } 400 401 #if OPENSSL_VERSION_NUMBER < 0x00907000L 402 #define EVP_X_STATE(evp) &(evp).c 403 #define EVP_X_STATE_LEN(evp) sizeof((evp).c) 404 #else 405 #define EVP_X_STATE(evp) (evp).cipher_data 406 #define EVP_X_STATE_LEN(evp) (evp).cipher->ctx_size 407 #endif 408 409 int 410 cipher_get_keycontext(const CipherContext *cc, u_char *dat) 411 { 412 Cipher *c = cc->cipher; 413 int plen = 0; 414 415 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { 416 plen = EVP_X_STATE_LEN(cc->evp); 417 if (dat == NULL) 418 return (plen); 419 memcpy(dat, EVP_X_STATE(cc->evp), plen); 420 } 421 return (plen); 422 } 423 424 void 425 cipher_set_keycontext(CipherContext *cc, u_char *dat) 426 { 427 Cipher *c = cc->cipher; 428 int plen; 429 430 if (c->evptype == EVP_rc4 || c->evptype == EVP_acss) { 431 plen = EVP_X_STATE_LEN(cc->evp); 432 memcpy(EVP_X_STATE(cc->evp), dat, plen); 433 } 434 } 435